Let's start from the Fluorine (F), which has 4 atoms on the right side: this means we must put a factor 4 in front of HF to balance the number of atoms of Fluorine.
Nowe we have 4 atoms of hydrogen, H, on the left side. Since we have a

on the right side (2 atoms), we must put a factor 2 in front of

, to balance the number of atoms of hydrogen.
So now the atoms of oxygen are also balanced (2 on both sides), as well as the atoms of Silicon (Si), so the balanced reaction is
Power is the rate of work that is done per time. Work is calculated from the product of force and the displacement. So, by using the definition of power and work, we can relate power with force, displacement and the time. We do as follows:
Power = Work / time
Power = Force x displacement / time
Power = 21 N (9 m) / 3 s
Power = 63 J /s = 63 W
Explanation:
When a bullet is fired from a rifle, the actual firing makes a distinctive sound, but people at a distance may hear a second because the bullet creates a shock wave , a little sonic boom( speed of this sonic boom is greater than the speed of sound). It is this sound only that is heard by the people at a distance from the gun.
Answer:
possible answer from edge
Explanation:
After World War II the only coal available to burn residentially, either for cooking or warmth, was of poor quality and contained large amounts of contaminants that made its fumes toxic. So when millions of homes in London burned this low quality coal and the local atmosphere over and around London stagnated, there was nowhere for the fumes to go. This stagnation allowed the toxic coal fumes to build up until they became physically harmful to humans and animals.